In ancient times, men on the battlefield actually pulled on each other's hair to inflict pain--you see, pain via hair-pulling is lasting pain, because sometimes, pain via blows or cuts, have a momentary stunning effect, and allowed the combatant to instantly regain his senses and fight more--but continuous pain from hair pulling is really painful. Sometimes, out of pure hatred and rage, stronger men were actually capable of tearing off another man's hair from his scalp. This was because men usually wore their hair long and uncut back then.
Thus it became the policy of a disciplined army (i.e. the Spartans, and other similar armies) to either tie their hair into braided knots or cut them off completely (other religious armies forbid cutting off of one's hair, so they were forced to tie them up). In fact, Herodotus wrote that Spartans combed their hair before a battle so
"they might die with their heads tidy." It is also the reason why modern day armies have men cut their hair very short (i.e. crew-cut, army-cut, white-side wall), so that the enemy cannot use the hair as leverage during hand to hand combat.
So as you can see, hair-pulling was once not exclusive for girls--before the advent of scientific warfare, everyone pulled on each other's hair during fighting.
-RODION